CVE-2026-103252n8n versions before 1.123.80, from 2.0.0 before 2.39.6, and from 2.40.0 before 2.40.1 contain an authorization bypass vulnerability in the credential test endpoint that resolves project-scoped variables without validating caller access. Attackers can specify an arbitrary project ID in the request body to interpolate sensitive variables into credential test requests sent to attacker-controlled hosts for exfiltration.